Vehicle

ABSTRACT

In a vehicle combination, a traction vehicle which can be used independently of the combination, is rigidly connected with a trailer vehicle. The rear wheels of the traction vehicle can be lifted from the road when the combination is coupled, the wheels of the traction vehicle being located at the ends of link rods pivoting about an axis and the link rods are connected with a pivoting driving system capable both of lifting the wheels from the road and providing a high quality rolling structure for the traction vehicle.

The present invention is directed to a vehicle as specified in theopening part of claim 1.

A vehicle of the mentioned species has been proposed in U.S. Pat. No.3,719,244 in order to eliminate the physical operating drawbacks of acombination composed of a traction vehicle and a trailer universallycoupled thereto through a drawbar, while the disadvantages of alarge-volume vehicle need not be put up with, such disadvantagesresulting mainly from poor maneuverability and considerable parkingspace requirements during short-range drives. With the known vehicle therear wheels of the traction vehicle must be lifted by separate liftingmeans. Also, driving of the rear axle of the traction vehicle whileuncoupled from the trailer is impossible.

The fundamental problem on which the proposals known from the prior artpublications are based can be observed, for instance, in the case ofcaravans. For practical use, two different basic types of such vehicleshave become widely accepted. The one basic type is the known combinationcomprising a traction vehicle which is generally a passenger car, and acamper. Such a combination offers the advantage that the camper may bedisconnected when it is not required so that the passenger car may beutilized without limitations for instance at the vacation place. Thedrawback of combinations resides in their comparatively poor handlingperformance. Due to the additional degree of freedom about the verticalaxis which extends through the drawbar coupling, so-called bending anglevibrations are made possible which promote jackknifing of the camperetc. Consequently, in most countries camper combinations are generallysubject to speed limitations.

Another common type of vehicle are the so-called camping cars. Suchcamping cars can be driven more easily and stably than combinations andalso offer the advantage that the persons in the traction vehicle may goto the living area even while travelling, which is impossible withcombinations already for statutory reasons. Of course, the drawbacks ofa camping car reside in the considerable space requirements, the largeweight, the consequent lack of parking space, high fuel costs etc., suchdrawbacks indeed prevailing when a smaller vehicle would be quitesufficient.

German Utility Model Specification 8,703,519 proposes a vehicle assemblyin which, by way of an extension and compression-proof connecting meansrigidly mounted on the body end of a passenger car used as tractionvehicle, a trailer can be rigidly coupled with said passenger car. Oneof the drawbacks of this vehicle assembly resides in that the rear axleof the traction vehicle and the single axle of the trailer must beclosely adjacent each other in the coupled state because by fiction oflaw only axles with a centre distance of not more than 1 m areconsidered as a single axle. However, only a design which satisfies thisrestriction will result in a marketable vehicle unit, because a vehicleunit provided with a total of three independent axles (with centredistances of more than 1 m) must not be driven with a normal driver'slicence for passenger cars. Larger vehicle units cannot be realized inaccordance with this structural principle, because heavier vehiclesrequire greater centre distances of the axles.

Similarly, DE-OS 3,129,203 proposes to couple a single-axle trailer witha conventional traction vehicle in such a way that the rear axle of thetraction vehicle and the axle of the trailer are disposed at a centredistance of less than 1 m.

In British Patent Specification 2,006,130 the specified drawbacks havebeen avoided. With this construction a single-axle trailer is connectedby way of an elongated rigid drawbar with a front wheel-driven tractionvehicle, wherein on the one hand the drawbar is rigidly connected withthe body platform and on the other hand roof portions of trailer andtraction vehicle are rigidly connected in such a way that the rearwardstructure of the traction vehicle inclusive of rear axle and rear wheelsis elevated. In this way there results a rigid vehicle unit in which therear axle including the wheels of the traction vehicle are lifted offthe road surface. One of the drawbacks of this design is the complexstructure and operation of the coupling, and another one is thedetrimental influence on the centre of gravity of the vehiclecombination when the rearward structure of the traction vehicle iselevated.

Finally, U.S. Pat. No. 3,825,089 proposes a vehicle combination in whichsubsequent to coupling of the traction vehicle and the trailer the rearaxle of the traction vehicle is elevated completely while the tractionvehicle remains in its horizontal position. It is a drawback of thisstructure that the entire rear axle is elevated, which on the one handnecessitates a solid-axle suspension system, and an unfavourabledisplacement of the centre of gravity is also caused thereby. Thephysical operating drawbacks of a solid rear axle do not permit itsemployment in high-grade passenger vehicles. Therefore, the knownconstruction is unsuited, for instance, for use in the combination of acomparatively fast traction vehicle and a camper.

German Patent Specification 867,057 discloses an apparatus forautomatically lifting the wheels of a truck axle off the road surface bymeans of suspension links which are pivotable about the axle and havethe wheels mounted on the free ends thereof, and by means of a swiveldrive with an hydraulic cylinder acting on an axle shaft through arack-and-pinion means.

Finally, DE-Al-3,009,284 discloses a trailer coupling with a couplingjaw on the traction vehicle and a drawbar projection on the trailer,said drawbar projection being pivotable relative to the coupling jaw;all of the plug-in connections for power transmission and power supplyto the trailer are integrated in a common coupling connector. A limitswitch provides the driver with information upon completion of coupling.

It is the object of the present invention to provide a vehiclecombination of the kind known from U.S. Pat. No. 3,719,244 in which therear wheels of the traction vehicle can be elevated without anyvariation of the normal vehicle heights or levels, especially theposition of the rearward structure, and without any unnecessarydisplacement of the centre of gravity so that a simple design andoperation of the rigid interlocking coupling between traction vehiclesand trailer becomes possible. Moreover, the construction is intended topermit the realization of a high-grade rear axle structure of thetraction vehicle and, in addition to that, of a rear wheel drive.Finally, in a vehicle combination of the above-described kind an optimumbrake function both in the coupled and the uncoupled condition is to beensured. The specified object is achieved by claim 1.

Advantageous embodiments of the invention are set out in the dependentclaims.

In the vehicle combination of the present invention the rear wheels ofthe traction vehicle in the state coupled to the trailer can be liftedoff the road by operation of the swivel drive without any change in theposition of the rearward structure and the rear axle and without anyrestrictions imposed on the design of the chassis of the tractionvehicle.

Since the planes of traction vehicle and trailer remain unchanged bothin the coupled and the uncoupled condition it is possible to realize arigid coupling of simple structure and easy handling.

Due to the design of the suspension system for the rear wheels of thetraction vehicle it is possible to optimize the characteristics of wheelposition such as toe-in and toe-out, camber, caster and the wheellifting curve while the capability of the wheels to be lifted off theroad in the coupled condition is not affected. Previously, thepossibility of lifting the wheels off the road had to be paid for by theuse of a solid axle with its inherent operational drawbacks and by thenecessity of elevating the wheels by lifting the solid axle off theroad, resulting in an unnecessary reduction of useful cargo space in thevehicle.

In view of the solid rigid coupling of both vehicles the legislatorpermits the stay of persons in the trailer while travelling. Inaccordance with a further improvement of the present invention slidingdoors may be provided in mutually opposed walls of both vehicles so asto permit passage from one vehicle to the other.

In a preferred embodiment of the present invention, the suspension linkson which the rear wheels of the traction vehicles are mounted areconfigured as longitudinal control arms and adapted to be swivelledabout a common axis which is parallel to the vehicle transverse axis.Such an arrangement offers the advantage that the swivel device forswivelling the suspension links and for lifting the wheels off the roadcan be designed with particular simplicity.

Within the scope of the present invention it is also conceivable thatthe coupling elements for coupling traction vehicle and trailer areconfigured such that coupling and uncoupling can be performed withoptimum ease and comfort.

In a preferred embodiment of the invention as specified in claim 11 thetrailer unit comprises two coupling arms which are constituted byportions of the trailer frame rails and which cooperate with couplingjaws integrated in the bumper of the traction vehicle. Such anembodiment offers the advantage that traction vehicle and trailer can becoupled together very easily, both vehicles always remaining in the sameplane during coupling and uncoupling. In a further particularlyadvantageous improvement of the vehicle combination of the presentinvention, electrical and hydraulic connecting members are integrated inthe coupling arms of the trailer and the coupling jaws of the tractionvehicle, respectively, so that subsequent to the coupling together oftraction vehicle and trailer both vehicles are automaticallyinterconnected electrically and hydraulically so that signalling meanssuch as stop lights, direction indicator lights and the trailer brakesystem may be operated from the traction vehicle without any additionalmeasures. In this connection, the configuration of the vehiclecombination according to claim 16 is particularly significant. Thisconfiguration ensures that even with the interlocked vehicle unitbraking with two brake circuits similar to a single vehicle isguaranteed so that legal requirements are met.

In a further preferred embodiment the wheel suspension elements of thetrailer are configured just like those of the rear wheels of thetraction vehicle. It is thus possible, if required, to provide fordriving of the trailer wheels and also to effect level control whichenables lowering onto the road for loading and unloading.

Below, the present invention will be explained in detail with referenceto the drawings, in which:

FIG. 1 is a vehicle in accordance with the invention in coupledcondition;

FIG. 2 illustrates the vehicle combination of FIG. 1 in uncoupledcondition;

FIG. 3 shows a modification of a trailer for a vehicle combination ofthe present invention, the modification being suited for carrying goods;

FIG. 4 is a rear view of a traction vehicle for a vehicle combination ofthe present invention;

FIG. 5 is a plan view showing the rear suspension system with swiveldevice of the traction vehicle illustrated in FIGS. 1, 2 and 4;

FIG. 6 is a section through a swivel device of the present inventionalong the line VI--VI in FIG. 5;

FIG. 7 is a section along the line VII--VII in FIG. 6;

FIG. 8 is a modification of a swivel drive for a wheel suspensionaccording to FIG. 5;

FIG. 9 is a modification of a rear suspension system for a tractionvehicle intended for a vehicle combination of the present invention;

FIG. 10 is a section along the line X--X in FIG. 9,

FIG. 11 is a section along the line XI--XI in FIG. 9;

FIG. 12 is a side view of the detail illustrated in FIG. 11;

FIG. 13 is a plan view illustrating frame and chassis of a trailer for avehicle combination of the present invention;

FIG. 14 is a plan view showing a coupling arm and a coupling jaw for avehicle combination of the present invention;

FIG. 15 is a section through a coupling arm plugged into a coupling jawcomprising an automatic locking device;

FIG. 16 is an electrical connecting portion disposed between couplingarm and coupling jaw;

FIG. 17 is a plan view illustrating frame and chassis of a trailer for avehicle combination of the present invention comprising means for levelcontrol; and

FIG. 18 is a section along the line XVIII--XVIII of FIG. 17.

FIG. 1 shows a vehicle 1 in coupled condition. It comprises afront-wheel driven traction vehicle 2 and a trailer 3 which in thepresent embodiment is a camper unit. The traction vehicle 2 comprises apair of rear wheels 4 which in the coupled state are lifted off the roadsurface 5. The trailer 3 comprises two pairs of wheels 6 and 7, thecentre distance between the two pairs of wheels preferentially beingless than 1 m, although it may be greater so as to obtain a desirableweight distribution over the various axles. The traction vehicle 2comprises two driven and steered front wheels 8 which also constitutethe front wheels of the coupled vehicle. The wheel pairs of the trailer3 constitute the rear wheels for the entire vehicle combination 1. Thecoupled vehicle combination is rigid and torsion resistant and exhibitsall of the physical operation advantages of a one-piece vehicle.

As will be apparent from FIG. 4, the vertically disposed rear wall 9 ofthe traction vehicle includes a door 10 of a roller shutter type capableof being opened when the traction vehicle is coupled with the trailer 3.Likewise, the trailer includes a roller shutter-type door (notillustrated) in its front side 11 facing the traction vehicle andsimilarly capable of being opened in the coupled condition so that anunobstructed through-way from the traction vehicle 2 into the trailer orcamper 3 is created.

FIG. 2 illustrates the vehicle combination shown in FIG. 1 in theuncoupled condition. The rear wheels 4 of the traction vehicle 2 are nowin the normal position so that the traction vehicle may be usedindependently of the trailer 3. The rear wheels 4 of the structure ofthe present invention may also be driven wheels so that, if desired, anoff-the-road vehicle is available. The trailer 3 is parked on its twopairs of wheels 6 and 7, and optionally it is possible to use supportingmembers (not illustrated herein). FIG. 2 indicates in dashed lines twoframe rails 12 shown one behind the other in the side view which attheir front ends terminate in coupling arms 13. In the coupled conditionthe coupling pins 13 engage in coupling jaws 14 integrated in a bumper15 of the traction vehicle 2. The coupling jaws 14 and the bumper 15,respectively, are fixedly joined to the non-illustrated frame of thetraction vehicle 2 so that a torsion resistant unit is formed when thecoupling of traction vehicle and trailer has been completed.

FIG. 3 shows an alternative of a trailer for a vehicle combination ofthe present invention, in which a superstructure 16 is mounted on top ofa frame 12 having coupling arms 13. The trailer 17, which is illustratedin the uncoupled condition, also has two pairs of wheels 6 and 7 and issupported on one or several supporting rollers 18.

FIG. 5 illustrates in plan view a rear suspension system for thetraction vehicle 2. The right rear wheel 4a and the left rear wheel 4bare each suspended from towed longitudinal control arms 19a and 19b. Thelongitudinal control arms 19a and 19b are rotatable about the commonaxis 20 which is parallel to the vehicle transverse axis. The ends 21aand 21b of the longitudinal control arms 19a and 19b are supported inbearings (not illustrated) and connected to a torsion bar 22 disposed onthe rotational axis 20. The torsion bar 22 is disposed within an axletube 23 to the ends of which bearings (not illustrated) are secured forsupporting the ends 21a and 21b of the longitudinal control arms 19a and19b. The axle tube 23 itself is connected to the frame of the tractionvehicle by means of clamps 24a and 24b. A swivel device 25 is disposedin the plane of symmetry extending between the wheels 4a and 4b, saidswivel device having its one end connected to the torsion bar 22 whilethe other end is connected to the vehicle body.

FIG. 6 is an enlarged sectional view along the line VI-VI of FIG. 5showing the swivel device. The left rear wheel 4b and the longitudinalcontrol arm 19b are merely indicated. The torsion bar 22 is connected toa lever 26 by means of two screw connections illustrated in FIG. 7. Thelever 26 extends to the outside through an opening 27 formed in the axletube 23 and has arcuate shape. The end of the lever remote from thetorsion bar 22 is connected to the piston rod 29 of an hydraulic liftingcylinder 30. The lifting cylinder 30 is supported through a joint 31 onthe frame 32 of the traction vehicle 2.

When the wheel 4b is deflected upwardly by a bump in the road 5 it willmove under positive guidance by the longitudinal control arm 19b on acircular arc about the axis 20. The longitudinal control arm 19b actslike a crank on the torsion bar 22 which is twisted right to its centreplane. In the centre plane it is prevented from further twisting bymeans of the screw connection illustrated in FIG. 7 and the lever 26which bears against the frame 32 through the piston rod 29, the liftingcylinder 30 and the joint 31. Therefore the other half of the torsionbar 22 extending to the right rear wheel 4a remains in a non-loadedstate so that any mutual influence between the rear Wheels 4a and 4b isprevented. When it is desired in the coupled condition of the vehiclesto lift the wheels 4a and 4b off the road 5, the lifting cylinder 30hydraulically extends the piston rod 29 so that the lever 26 andtherefore the torsion bar 22 will turn towards the front end, i.e.clockwise as viewed in FIG. 6. Together with the turning movement of thetorsion bar 22 the longitudinal control arms 19a and 19b fixedlyconnected thereto will also be moved, and it is a specific advantagethat no spring forces need be overcome due to the direct linking of thelever 26 to the torsion bar. Driving of the hydraulic lifting cylinder30 may be effected automatically as soon as the vehicles are coupled toeach other.

FIG. 8 illustrates a modification for twisting the torsion bar 22disposed in the axle tube 23. In this case, the axle tube 23 is formedwith two openings 27 and 32. Levers 26 and 33 extend through theopenings 27 and 32, and pneumatic bellows 34 and 35 are disposed on theends of the levers remote from the torsion bar 22. The bellows 34 and 35bear against the frame 32 of the traction vehicle 2. When the wheels areto be lifted off the road 5 pressurized air is applied to the bellows 34so that the torsion bar 22 is twisted via the lever 26. When the wheelsare to be lowered pressure is released from the bellows 34 whilepressurized air is applied to the bellows 35. The torsion bar 22 is thenreturned to its initial position via the lever 33. It is an advantage ofthis arrangement that the torsion bar 22 is not rigidly supportedthrough an incompressible medium as in the case of the hydraulic liftingcylinder 30 but that an additional spring action is created bysupporting the torsion bar via the pneumatic bellows 34 and 35,respectively. In certain cases it may be possible therefore to dimensionthe torsion bar 22 somewhat weaker which results in a correspondingreduction in weight.

FIG. 9 is a plan view of an alternative embodiment of a rear wheelsuspension. The rear wheels 4a and 4b are likewise suspended from towedlongitudinal control arms 19a and 19b. Also, the ends 21a and 21b of thelongitudinal control arms are rotatably supported in bearings mounted onthe axle tube 23. In contrast to the embodiment illustrated in FIG. 5,the axle tube is not fixedly connected to the frame 32a but isjournalled in two bearings 37. Axial displacement of the axle tube isprevented by a lock washer 38 which is accommodated in a groove formedin the bearing 37.

As indicated in dashed lines in FIG. 9, the ends 21a and 21b of thelongitudinal control arms 19a and 19b are respectively connected toprofile bars 40a and 40b, each profile bar being somewhat shorter thanhalf the length of the axle tube 23. As will be apparent from FIG. 10,which is a section along the line X--X of FIG. 9, the profile bar 40ahas essentially triangular cross-section. Rubber pads 42a, b and c aredisposed on the sides of the triangle to bear against the inner wall ofthe axle tube 23 via positive abutments 43. When the longitudinalcontrol arm and the profile bar connected thereto are twisted, therubber pads 42a, b and c act as spring elements which react to twistingof the profile bar 40a relative to the axle tube 23 by generating arestoring force. For simple undercarriages the rubber elements may alsoprovide a damping function due to their material absorption.

The axle tube 23 is connected with a lever 26 which at its end 28 remotefrom the axle tube is connected with the frame 32a of the tractionvehicle 2 via a piston rod 29 and an hydraulic lifting cylinder 30 and alink 31.

As will be apparent from FIG. 10 in conjunction with FIG. 9, in thepresent embodiment the swivel drive in the form of the lifting cylinder30 and the piston rod 29 is disposed opposite the longitudinal controlarms 19 so that the piston rod 29 must be retracted for lifting thewheels 4a and 4b. When the piston rod 29 is retracted by the liftingcylinder 30 the lever 26 and hence the axle tube 23 will move clockwiseso that, via the abutments 43, the rubber pads 42a, b and c and theprofile bars 40a and 40b, the longitudinal control arms 19a and 19b areturned and the wheels are lifted thereby.

FIG. 13 illustrates in plan view the undercarriage of the trailer 2 or17 illustrated in FIG. 1 or FIG. 3, respectively. The wheels 6a and 6bor 7a and 7b, respectively, are guided on towed longitudinal controlarms 45a, 45b and 46a, 46b. The frame rails 12a and 12b terminate incoupling arms 13a and 13b which are inserted in coupling jaws 14a and14b provided on the traction vehicle 2, where they are retained by wayof locking means 48a and 48b. The enlarged detail XV is illustrated inFIG. 15.

A coupling arm 13 is provided with a transverse hole 50 and terminatesin a bevelled butting face 52 at the front end of the pin.Preferentially, the cross-section of the coupling arm and of thecorresponding coupling jaw 14 may be rectangular or round. On thecoupling jaw 14 there is provided a locking device 48 which consistsessentially of a spring-loaded bolt having a bevelled butting face 55 onthe forward end thereof. When the trailer 3 or 17 is parked horizontallyby corresponding alignment of a guide roller 18, the coupling arm 13will be at the same level as the coupling jaw 14 on the traction vehicle2. When the driver of the traction vehicle 2 reverses the vehicle thecoupling arm 13 or both coupling arms 13 in case of an embodimentcomprising two coupling arms, respectively, is/are inserted into therespective coupling jaw, the bevelled butting face 52 deflecting thebolt 54 via the bevelled butting face 55 against the biasing force of aspring 56. As soon as the coupling arm 13 is fully inserted into thecoupling jaw 14 the bolt 54 will be in alignment with the hole 50 andwill lock in the hole 50 under the action of the spring 56. In this wayautomatic locking is ensured. As illustrated in FIGS. 14 and 16, theelectric circuits of traction and. trailer vehicle can be connected andthe transmission of brake power can be ensured at the same time.

The bolt 54 may be connected to a linkage 58 so that it may be pulled toa release position, optionally by remote control.

A signal light switch 49 informs the driver via an indicator lamp (notillustrated) in the dashboard of the traction vehicle 2 that thecoupling operation has been completed and the coupling made secure.

As shown in FIG. 14, the hollow coupling arm 13 and the coupling jaw 14are provided in their interior with an hydraulic cylinder 62 and a rod66 to ensure mechanical/hydraulic transmission of the brake power.

The hydraulic cylinder 62 comprises a piston 63 with a pin 61 projectingin the direction of the coupling arm 13. Pressure is applied to thepiston 63 via an hydraulic conduit 60 against the action of acompression spring 64. Upon an increase in pressure within the conduit60 due to actuation of the hydraulic brake of the traction vehicle 2through the brake master cylinder the pressure in conduit 60--in thecoupled condition of traction vehicle and trailer--is mechanicallytransmitted via the pin 61 to the rod 66 and hence to the link 70 and tothe brake master cylinder 72 of the trailer which also includes a fluidreservoir 73. By means of the pressure developed thus in the brakemaster cylinder 72 the wheel brake cylinders (not illustrated) of thetrailer 3 are actuated. When the brake in the traction vehicle isreleased the restoring springs in the wheel brake cylinders restore thebrake shoes and thus the piston in the brake master cylinder 72, thelink 70 and the rod 66 to the brake readiness position.

The pressure in the hydraulic conduit 60 is applied through a thirdchamber of the brake master cylinder of the traction vehicle, saidmaster cylinder by the way being conceived for a dual circuit brakesystem of the traction vehicle. Alternatively, such pressure may also beapplied through an input cylinder in the traction vehicle which isassociated with a commonly used tandem master cylinder for a dualcircuit brake system of the traction vehicle. With such a design of thebrake system the wheels 4a and 4b of the traction vehicle are alsobraked irrespective of the fact that in the coupled state these wheelsare lifted off the road. Due to the mechanical/hydraulic transmission ofthe braking pressure from the third chamber of the brake master cylinderor from the input cylinder of the traction vehicle to the brake mastercylinder 72 of the trailer, the coupled vehicle combination is brakedwith a dual circuit brake system as in the case of a unitary vehicle,because even a small hydraulic brake pressure in the traction vehicle isenhanced and directly transmitted to the brake master cylinder 72 of thetrailer.

The brake system can be adjusted both initially and during latermaintenance by making the rod 66 length-variable. In this way the rodmay be set to a length where in the coupled condition the pin 61 willmove the rod 66 already at the slightest actuation of the hydraulicbrake of the traction vehicle. Due to the brake pressure in conduit 60the pin 61 may be extended up to 3/4 of its length. When the brakingoperation has been terminated the pin is urged back by the spring 64into the hydraulic cylinder 62 by about half its overall length. In thisway an automatic brake pressure balance is caused in the brake systemsof the vehicles 2 and 3.

According to FIG. 16, the end face of one of the two coupling arms 13 isprovided with an electrical contact 74 which upon coupling is broughtinto engagement with a corresponding, tab-like contact 76 in thecoupling jaw 14. The contact 76 causes automatic making of theelectrical connection between traction vehicle 2 and trailer 3 or 17,respectively. Additionally or alternatively, the trailer may also have aseparate power supply.

As shown in FIG. 17, a chassis of the trailer is equipped with two axleassemblies of the kind illustrated and described in FIG. 9; instead ofthe swivel drive by means of hydraulic lifting cylinders, adjustment isprovided by means of a threaded spindle 78.

Of course, it is also possible to employ instead of the manuallyoperated threaded spindle a configuration with a power-assisted liftingcylinder as described with reference to FIGS. 5 to 11.

According to FIG. 18, the lever 26 of each axle which is connected withthe axle tube 23 is joined to the threaded spindle by way of a threadedbush 82 pivotable about a swivel joint 80. The threaded spindle 78 isadditionally guided in a bearing 86 mounted on a cross arm 84. On theend of the threaded spindle 78 there is mounted a universal joint 88 forconnecting the threaded spindle to a shaft 89. The shaft 89 is guided ina bearing 90 and may be rotated by a crank 92. When the shaft 89 isrotated the threaded spindle 78 will also be rotated via the universaljoint 88. The position of the threaded spindle 78 is fixed by means ofthe bearing 86 relative to the frame or the frame rails 12 of thevehicle. When the threaded spindle 78 is rotated the threaded bushes 82will therefore be moved relative to the vehicle frame so that the lever26 is rotated and thus, via the axle tube 23 and the operationsexplained with reference to FIG. 9, the positions of the longitudinalcontrol arms 45a to 46b relative to the vehicle frame are varied. As thewheels 6a to 7b of the trailer 2 or 17, respectively, rest on the roadsurface 5 and bear the vehicle weight, rotation of the longitudinalcontrol arms 45a to 46b will not result in a lifting or lowering of thewheels but in a lifting or lowering of the entire vehicle. In this way adesired levelling and hence adaptation to different load conditions maybe realized. For purposes of loading and unloading it is also possibleto lower the trailer completely onto the ground.

For the very first time, the vehicle of the present invention enables acombination of a traction vehicle and a trailer which can be coupled anduncoupled in a simple, rapid and comfortable way and in which the rearwheels of the traction vehicle which are not required in the coupledstate can be lifted off the road surface without also elevating the rearaxle, while the loading space in the traction vehicle is not reduced andan inferior-quality chassis construction of the traction vehicle neednot be put up with.

I claim:
 1. A vehicle comprising a traction vehicle (2) having drivenfront wheels (8), rear wheels, and a brake circuit, which by way of acoupling assembly which includes at least one coupling jaw (14) fixedlymounted on the traction vehicle, is adapted to be rigidly coupled in anoperative connection with at least one coupling arm (13) one a trailer(3) having at least two wheels and a brake circuit wherein in thecoupled state the rear wheels of the traction vehicle which aresuspended from suspension links (19a, 19b) are lifted off the roadsurface and the operative connection between the at least one couplingjaw (14) and the at least one coupling arm (13) is locked automaticallyupon coupling, and the rear wheels (4) of the traction vehicle (2) arelifted by a swivel drive common to both suspension links (19a, 19b) whenthe coupling operation has been completed, the operative connectioncomprising electrical contacts integrated in the at least one couplingjaw (14) and the at least one coupling arm (13) for automatically makingan electrical connection between the traction vehicle and the trailerupon coupling thereof, upon coupling of the at least one coupling jawand the at least one coupling arm an operating connection is providedbetween the brake circuit of the traction vehicle and the brake circuitof the trailer (3), and the lifting of the rear wheels (4) of thetraction vehicle after completion of the coupling operation isautomatically performed by the swivel drive (25).
 2. Vehicle as claimedin claim 1, characterized in that the suspension links are longitudinalcontrol arms (19a,b) adapted to be pivoted about a common axis (20). 3.Vehicle as claimed in claim 2, characterized in that each of saidlongitudinal control arms is connected with a torsion bar (22) disposedin parallel with said axis (20).
 4. Vehicle as claimed in claim 2 orclaim 3, characterized in that the two longitudinal control arms (19a,b)which are adapted to be pivoted about a common axis (20) are connectedwidth each other by a centrally disposed torsion bar (22).
 5. Vehicle asclaimed in claim 2, characterized in that the two longitudinal controlarms (19a,b) which are adapted to be pivoted about a common axis (20)are connected with each other by a profiled transverse member. 6.Vehicle as claimed in claim 2, characterized in that the longitudinalcontrol arms (19a,b) are rotatably mounted on the ends of an axle tube(23) and are connected with profiled rods (40a,b) bearing against theinner wall of the axle tube by means of resilient rubber pads (42a,b,c).7. Vehicle as claimed in claim 3 characterized in that the swivel drive(25) comprises a lever (26) which is connected with the torsion bar (22)and adapted to be swivelled by means of the swivel drive at its endremote from the torsion bar.
 8. Vehicle as claimed in claim 5,characterized in that the swivel drive (25) comprises a lever which isconnected with the profiled transverse member and which is adapted to beswivelled by means of the swivel drive at its end remote from theprofiled transverse member.
 9. Vehicle as claimed in claim 6,characterized in that the swivel drive (25) comprises a lever (26) whichis connected with the axle tube (23) and which is adapted to beswivelled by the swivel drive at its end remote from the axle tube. 10.Vehicle as claimed in claim 1, characterized in that the swivel drive isa lifting cylinder (30) which is preferentially controlled by anelectrically operated hydraulic pump.
 11. Vehicle as claimed in claim 1,characterized in that the trailer comprises two coupling arms (13a,b)constituted by extensions of frame rails (12a,b) on the trailer, andthat the traction vehicle (2) comprises two mating coupling jaws(14a,b).
 12. Vehicle as claimed in claim 11, characterized in that thetwo coupling jaws (14a,b) are integrated in the rear bumper (15) of thetraction vehicle.
 13. Vehicle, particularly as claimed in claim 1,characterized in that the traction vehicle (2) includes one of athree-chamber brake master cylinder or a dual-chamber brake mastercylinder with an input cylinder such that the traction vehicle in theuncoupled state has a dual circuit brake system, and that in the trailer(3) there is provided a separate brake master cylinder (72) adapted tobe actuated through the at least one coupled jaw and the at least onecoupled arm by one of the third chamber of the three-chamber brakemaster cylinder and the input cylinder.
 14. Vehicle as claimed in claim13, characterized in that a coupling arm (13) of the trailer has a rod(66) disposed therein which is actuated by means of an hydrauliccylinder (62) disposed in the coupling jaw (14) for energizing anhydraulic brake cylinder (72) and thus the brake system of the trailer.15. Vehicle as claimed in claim 14, characterized in that the hydrauliccylinder (62) comprises a pin (61) which is extended upon actuation of apedal brake of the traction vehicle in the direction of the trailer (3)so as to ensure permanent readiness to brake.
 16. Vehicle as claimed inclaim 14 characterized in that the rod (66) of the trailer (3) isvariable in length so as to permit an adjustment of the brake system ofthe trailer (3).
 17. Vehicle as claimed in claim 15 characterized inthat upon release of the pedal brake, the rod (66) and thus the pin (61)are pushed back into the hydraulic cylinder (62) to the readinessposition thereof by the restoring springs of the wheel brake cylindersof the trailer (3).
 18. Vehicle as claimed in claim 1 wherein thetrailer comprises wheel suspension links with longitudinal control arms(45a,b) that are rotatably mounted on the ends of an axle tube (23). 19.Vehicle as claimed in claim 18, characterized in that the suspensionlinks of the trailer include a swivel drive for rotating the suspensionlinks, the trailer swivel drive is connected to a means through whichthe rotation of the suspension links can be utilized for level controlof the trailer.
 20. Vehicle as claimed in claim 1, characterized in thatthe at least one coupling arm of the trailer has a transverse hole (50)and that the at least one mating coupling jaw (14) includes therein aspring-loaded pin (54) with a butting face (55), said pin upon insertionof the at least one coupling arm into the at least one coupling jawbeing pushed back against the biasing action of a spring (56) andlatching in said transverse hole (50) of the at least one coupling arm(13) for automatic locking therein.
 21. Vehicle as claimed in claim 1,characterized in that the traction vehicle comprises a rear wall havinga door (10) and that a front wall of the trailer is likewise providedwith a door so as to create a through-way between traction vehicle andtrailer in the coupled state thereof.
 22. Vehicle as claimed in claim21, characterized in that the door (10) of traction vehicle and thedoors of the trailer are designed as sliding doors.
 23. The vehicle asclaimed in claim 18 wherein said trailer further comprises a lever (26)that is connected with the axle tube (23) and which is adapted to beswiveled to thereby elevate the axle tube (23).
 24. The vehicle asclaimed in claim 23 wherein said trailer further comprises a threadedspindle (78) for swiveling the lever (26).